Claims
- 1. A tuning apparatus for a synchronously pumped dye laser having a resonator cavity in which a laser light beam resonates along an axis comprising:
- a tuning plate having at least one surface upon which said laser light beam is incident and comprised of birefringent material having two different indices of refraction along two principal displacement directions and having an optic axis and having a thickness defined according to the following equation: ##EQU19## where, .lambda.=the wavelength of said resonating light which will have minimum loss and defining the lasing wavelength;
- .DELTA.n=the difference in the indices of refraction along the two principal displacement directions in said plate at the wavelength .lambda. defining the birefringence of said plate;
- T=the thickness of the birefringent tuning plate;
- m=an order number indicating a number of full wavelengths of phase retardation said resonating light will experience in passing through said tuning plate;
- .theta.=an angle of incidence of said resonating laser light beam in said cavity on said surface of said plate;
- n=the average index of refraction between said two different indices of refraction of said birefringent tuning at the wavelength .lambda.; and
- .phi.=a tuning angle equal to .alpha.+.pi./4 where .alpha. is the angle between the projection of said optic axis of said birefringent plate on said surface of the birefringent plate upon which light beam is incident to the plane of incidence containing both said axis said light beam and a normal to said surface;
- said thickness T being chosen from the range from 0.1 mm to 0.5 mm such that a family of tuning curves are defined, each defining a single mode of lasing and having a single order number m and defining a relationship between said tuning angle and said resulting lasing wavelength, said thickness T being selected such that at least one said tuning curve covers a substantial portion of a desired range of lasing wavelengths; and
- means optically coupled to said tuning plate for suppressing satellite lobes in an autocorrelation function showing pulse shape for said synchronously pumped dye laser.
- 2. The apparatus of claim 1 wherein said thickness T is chosen such that said tuning angle stays smaller than the tuning angle at which tuning anomalies in the form of jumps to different wavelengths and different polarizations occur at the ends of a tuning range said tuning range defined as the range of tuning angles .phi. which cover the selected tuning curves and wherein said means for suppressing satellite lobes is a thickness of KZF1 glass from 1 to 1.5 millimeters thick optically contacting two opposite surfaces of said tuning plate through which said resonating light beam passes.
- 3. The apparatus of claim 1 wherein the thickness is chosen such that the sensitivity of the wavelength .lambda. to changes in the tuning angle .phi. is not so great as to make it difficult to achieve lasing at any particular wavelength but not so insensitive that very large changes in the tuning angle need to be made to change the wavelength of lasing appreciably.
- 4. The apparatus of claim 1 wherein the thickness T of the plate is chosen so that the single order tuning curve which covers the desired tuning range allows tuning which is substantially linear over the tuning range of interest.
- 5. The apparatus of claim 1 wherein the thickness T of the plate is chosen such that the center of the tuning range is at a tuning angle of approximately 5 degrees.
- 6. The apparatus of claim 1 wherein the thickness T of the plate is chosen to be 0.29 millimeters.
- 7. A synchronously pumped dye laser comprising:
- a dye jet;
- means for pumping said dye jet to excite lasing;
- a resonator cavity including at least two mirrors and defining an axis for a resonating light beam defining an axis between said two mirrors which passes through said dye jet;
- a tuning plate of birefringent material having two parallel surfaces upon which said light beam resonating in said cavity is incident and having two different indices of refraction along two principal displacement directions having two different indices of refraction along two different principal displacement directions having a predetermined thickness in the range from 0.1 mm to 0.5 mm defining a family of tuning curves, each curve defining a single mode of lasing and chosen so that a single mode tuning curve in a family of tuning curves inherently defined by the selection of the thickness T of said plate covers a range of desired lasing wavelengths for the particular dye being used, said first tuning plate being located such that said resonating light beam passes through said first tuning plate and makes Brewster's angle with a normal to the surface of said first plate; and
- means optically coupled to said tuning plate for suppressing satellite lobes in an autocorrelation function showing pulse shape for said synchronously pumped dye laser.
- 8. The apparatus of claim 7 wherein the thickness of said first tuning plate is 0.297 millimeters and further comprising a second tuning plate of birefringent material wherein the thickness of the second tuning plate is four times the thickness of said first tuning plate.
- 9. The apparatus of claim 8 further comprising a third tuning plate of birefringent material having a thickness which is an integer multiple of the thickness of said second tuning plate and situated along said axis in said resonator cavity such that light resonating in said cavity must pass through said third tuning plate, and having an optic axis which is substantially parallel to the optic axes of said first and second tuning plates, and oriented so that the surfaces of said third tuning plate upon which light is incident form Brewster's angle between said axis and the normal to said surfaces.
- 10. The apparatus of claim 7 where the thickness T is selected using the following equation: ##EQU20## where, .lambda.=the wavelength of the light which will have minimum loss;
- .DELTA.n=the difference in the indices of refraction along the two principal displacement directions in said first tuning plate defining the birefringent of said plate;
- T=the thickness of the birefringent first tuning plate;
- m=an integer indicating a number of full wavelengths of phase retardation said light will experience in passing through the birefringent first tuning plate defining an order number;
- .theta..sub. = an angle of incidence of said laser light beam in the cavity on a surface of said first tuning plate;
- n=an average index of refraction of said birefringent material as between said two different indices of refraction; and
- .phi.=an angle equal to .alpha.+.pi./4 where .alpha. is an angle between a projection of an optic axis of said birefringent first tuning plate on said surface of said birefringent first tuning plate upon which said resonating light beam is incident to a plane of incidence containing both a direction of propagation vector of said resonating light beam and a normal to said surface;
- said thickness T defining a family of tuning curves each of which has a different value m and defining a single mode of lasing, each said tuning curve called a single order tuning curve, T being chosen such that a single order tuning curve covers the range of lasing wavelengths of interest within a predetermined rang of tuning angles, .phi. centered around approximately 5.degree..
- 11. The apparatus of claim 10 wherein said first tuning plate is coated with a nonbirefringent index matching material on all surfaces through which light resonating in said cavity passes.
- 12. The apparatus of claim 10 wherein the thickness, is chosen such that the sensitivity of the wavelength .lambda. to changes in the tuning angle .phi. is not so great as to make it difficult to achieve lasing at any particular wavelength by choosing an appropriate tuning angle, .phi., but not so insensitive that very large changes in the tuning angle are necessary to change the wavelength of lasing appreciably.
- 13. The apparatus of claim 12 wherein the thickness, T, of the plate is chosen such that the center of said tuning range is at a tuning angle of approximately 5 degrees.
- 14. The apparatus of claim 10 wherein the thickness, T, of the plate is chosen so that the single order tuning curve which covers the desired dye tuning range allows tuning which is substantially linear over the tuning range of interest.
- 15. The apparatus of claim 14 wherein the thickness, T, of the plate is chosen such that the center of said tuning range is at a tuning angle of approximately 5 degrees.
- 16. The apparatus of claim 10 wherein the thickness, T, of the plate is chosen such that the center of said range is at a tuning angle of approximately 5 degrees.
- 17. A tuning apparatus for a dye laser having a resonator cavity having laser light resonating therein along an axis comprising:
- a first tuning plate of birefringent material having a surface on which said light is incident and having two different indices of refraction along two different principal displacement directions and having an optic axis having a thickness defined according to the following equation: ##EQU21## where, .lambda.=the wavelength of said resonating light which will have minimum loss;
- .DELTA.n=the difference in the indices of refraction along the two principal displacement directions in the anisotropic material of said first tuning plate at the wavelength .lambda. defining the birefringence thereof;
- T=the thickness of said first tuning plate;
- m=an order number indicating the number of full wavelengths of phase retardation said light will experience in passing through the birefringent plate;
- .theta.=the angle of incidence of said axis on said surface of said first tuning plate;
- n=the average index of refraction between said two different indices of refraction of the birefringent material of said plate at the wavelength .lambda. for said resonating light; and,
- .phi.=an angle equal to .alpha.+.pi./4 where .alpha. is the angle between the projection of said optic axis of said birefringent first tuning plate on said surface of said birefringent first tuning plate upon which said resonating light is incident to a plane of incidence containing both said axis and a normal to said surface;
- where the thickness T of said birefringent first tuning plate defines a family of tuning curves each of which has a different order value of m and defines a relationship between said tuning angle and the wavelength of lasing where said resonating light suffers minimum losses in said cavity, where T is between 0.1 mm and 0.5 mm and is chosen such that a single order tuning curve covers a desired range of lasing wavelengths of said laser light for a single dye used in said dye laser and within a predetermined range of tuning angles, .phi., centered at approximately 5.degree.;
- and further comprising two substrates of nonbirefringent matches having an index of refraction which substantially matches the average index of refraction of said birefringent first tuning plate, said two substrates optically contacting the surfaces of said birefringent first tuning plate through which light resonating in said cavity passes.
- 18. The apparatus of claim 17 first comprising second and third birefringent tuning plates which have thicknesses which are first and second even integer multiples of the thickness of said first birefringent plate and wherein said first, second and third birefringent tuning plates have surfaces upon which said resonating light is incident which are oriented at Brewster's angle to the light beam resonating in said resonator cavity. PG,76
- 19. The apparatus of claim 18 further comprising a nonbirefringent plate at Brewster's angle to the light resonating in said cavity and made of a material such that light passing therethrough having other than p-polarization will suffer losses.
- 20. The apparatus of claim 19 wherein the thicknesses of said second and third birefringent tuning plates are integer multiples of the thickness of said first birefringent tuning plate within a selected tolerance of no larger than plus or minus 5 microns, said thickness tolerance being selected so as to not cause losses of intensity of the light resonating in said resonator cavity greater than a 0.5% single path loss in intensity.
- 21. The apparatus of claim 20 wherein said second birefringent plate is parallel to said first birefringent plate to within a second predetermined tolerance and said third plate is parallel to said first plate to within a third predetermined tolerance.
- 22. The apparatus of claim 21 wherein said second and third predetermined tolerances are such that power losses for light resonating in said resonator cavity are less than or equal to the power losses created by deviations of the thicknesses of said second and third birefringent plates within said first tolerance away from being exact integer multiples of the thickness of said first tuning plate.
- 23. The apparatus of claim 22 wherein said thickness of said birefringent fist tuning plate is chosen to keep a free spectral range of said dye laser from being smaller than a predetermined level where the free spectral range is defined as the spacing in Gigahertz defining the frequency of said lasing wavelength between the tuning curves of different order number M.
- 24. The apparatus as defined in claim 23 wherein said predetermined level for said free spectral range is defined such that no tuning curve overlaps a gain profile band of the particular dye in use within the range of tuning angles along a single order tuning curved selected for operation of said laser.
- 25. The apparatus of claim 24 further comprising a non-birefringent glass plate tuning anomaly suppressor located in said resonator cavity at Brewster's angle so that light resonating in said cavity must pass through said non-birefringent glass plate so as to impose losses on any light passing therethrough that has other than p-polarization.
- 26. The apparatus of claim 17 further comprising a non-birefringent glass plate tuning anomaly suppressor located in said resonator cavity at Brewster's angle so that light resonating in said cavity must pass through said non-birefringent glass plate so as to impose losses on any light passing therethrough that has other than p-polarization.
- 27. The apparatus of claim 17 wherein said first, second and third birefringent plates are aligned such the wavelength error caused by errors in thickness of said second and third birefringent plates away from being exact integer multiples of the thickness of said first birefringent plate and caused by errors in parallelism of said first, second, and third birefringent plates is zero at tuning angle, .phi., of -8 degrees or +18 degrees or both.
- 28. A tuning apparatus for a synchronously pumped dye laser having a resonator cavity and a beam of coherent laser light resonating therein along an axis passing through a jet of dye, said tuning apparatus for providing capability to tune the wavelength of said beam causing said laser to lase at selected wavelengths within a tuning range along a tuning curve, comprising:
- a first birefringent plate of material having a surface upon which the resonating laser light is incident and having an optic axis and having a thickness defined according to the following equation: ##EQU22## where, .lambda.=the wavelength of the light which will have minimum loss;
- .DELTA.n=the birefringence of the plate or the difference in the indices of refraction along the two principal displacement directions in the anisotropic material at the wavelength .lambda.;
- T=the thickness of the birefringent plate;
- m=an order number indicating the number of full wavelengths of phase retardation the light will experience in passing through the birefringent plate;
- .theta.=the angle of incidence of the laser light beam in the cavity on the surface of the plate;
- n=the average index of refraction of the birefringent material at the wavelength w; and
- .phi.=a tuning angle equal to .alpha.+.pi./4 where .alpha. is the angle between the projection of said optic axis of the birefringent platen on the surface of the birefringent plate upon which said resonating light is incident and the plane of incidence containing both the direction of a propagation vector of the resonating light and a normal to said surface upon which said incident light is resonant;
- a second birefringent plate having a thickness which is a first integer multiple of the thickness of said first birefringent plate, and located in said resonator cavity so as to be parallel to said first birefringent plate and so that light passing through said first birefringent plate passes through said second birefringent plate;
- a third birefringent plate having a thickness which is a second integer multiple of the thickness of said first birefringent plate, and located in said resonator cavity so as to be parallel to said first birefringent plate and so that light passing through said first birefringent plate passes through said second birefringent plate;
- said thickness of said first birefringent plate defining a family of tuning curves, said thickness being chosen such that a single order tuning curve covers a range of lasing wavelengths of said dye, said range centered at a predetermined angle selected to reduce wavelength error over a predetermined range of tuning angles, .phi., between the wavelength of lasing by said laser if said second and third birefringent plates were not present and the actual lasing wavelength with said second and third birefringent plates present, said wavelength errors caused by thickness errors in the manufacturer of said second and third birefringent plates causing them to have other than exact integer multiples of the thickness of said first birefringent plate and by lack of parallelism between said second and third birefringent plates to said first birefringent plate; and
- means including a substrate of nonbirefringent KZF1 glass of a thickness from 0.8 to 1.5 mm coating each surface of said first birefringent plate through which light resonating in said cavity passes for suppressing satellite lobes in the autocorrelation function of pulse shape for pulses of greater than 2 picoseconds duration in said synchronously pumped dye laser.
- 29. The apparatus of claim 28 wherein said thickness of said first birefringent plate is chosen to keep a free spectral range, defined as the spacing in Gigahertz between different order tuning cures, from being smaller than an acceptable level for said tuning range, where said acceptable level is defined as no more than one tuning curve intersecting the gain profile band of the particular dye used in said laser within the range of tuning angles, .phi., of the intersection between the selected tuning curved for operation and the gain profile band of the particular dye being used.
- 30. The apparatus of claim 29 further comprising at least one non-birefringent plate means located in said resonator cavity so as to intersect the beam of light resonating in said cavity at Brewster's angle for imposing sufficient losses on light of selected polarizations to eliminate or minimize jumps of lasing activity to non-full order wavelength solution between tuning curves when said laser is tuned under predetermined conditions to lase at wavelengths near the ends of the tuning range of a single tuning curve.
- 31. The apparatus of claim 30 wherein said second and third birefringent plates have a tolerance on thickness indicating the maximum error in thickness from an integer multiple of the thickness of said first birefringent plate and wherein the tolerance on the thickness of said second and third birefringent plates is sufficient to insure that first pass losses imposed upon light resonating in said resonant cavity do not exceed 0.5%.
- 32. The apparatus of claim 31 wherein the alignment of said second and third birefringent plates in parallel relationship to said first birefringent plate has a tolerance indicative of the maximum allowable error in parallelism and wherein the tolerance on the parallel relationship of said second and third birefringent plates is such that losses imposed upon light resonating in said resonant cavity caused by said parallelism errors is no greater than a fraction of the losses imposed by thickness error.
- 33. A tuning apparatus for a dye laser having a resonator cavity in which a laser light beam is resonating along an axis comprising:
- a tuning plate of birefringent material having at least one surface oriented at Brewster's angle to the axis of said resonating light beam and upon which said laser light beam is incident and having at least two different indices of refraction along at least two different principal displacement directions, and having an optic axis a thickness defined according to the following equation: ##EQU23## where, .lambda.=the wavelength of the light which will have minimum loss;
- .DELTA.n=the difference in the indices of refraction along the two principal displacement directions in the anisotropic material at the wavelength .lambda. defining the birefringence of said plate;
- T=the thickness of the birefringent tuning plate;
- m=an order number indicating the number of full wavelengths of phase retardation the light will experience in passing through the birefringent plate;
- .theta.=an angle of incidence of said laser light beam on said surface of the plate;
- n=the average index of refraction between said two indices of refraction of the birefringent material at the wavelength .lambda.;
- .phi.=a tuning angle equal to .alpha.+.pi./4 where .alpha. is the angle between the projection of said optic axis of said birefringent plate on said surface of the birefringent plate upon which the light beam is incident to a plate of incidence containing both said axis along which said light beam is resonating and a normal to said surface; and
- n=the average index of refraction between said two different indices of refraction for said tuning plate at wavelength .lambda. for said light beam'
- said thickness T being chosen so as to define a family of tuning curves, each having a different order number m and being chosen such that a single order tuning curve covers a desired range of lasing wavelengths of interest within a predetermined range of said tuning angles, .phi.;
- a plate of non-birefringent material oriented at Brewster's angle to said light beam resonating in said cavity and positioned such that said axis passes therethrough; and
- further comprising a layer of non-birefringent transparent material having an index of fraction which substantially matches at least one index of refraction of said plate of birefringent material, and coating at least one surface of said first birefringent plate through which said light beam resonating in said cavity passes and having a predetermined thickness sufficient to reduce satellite lobes in the autocorrelation function of pulse shape for pulses of greater than 2 picoseconds duration.
- 34. A tuning apparatus for a solid state laser having a resonator cavity having a resonating light beam of laser light therein defining an axis comprising:
- a first tuning plate of birefringent material having two different indices of refraction along two different principal displacement directions and having an optic axis and having at least two surfaces upon which said resonating light beam is incident having a thickness T defined according to the following equation: ##EQU24## where, .lambda.=the wavelength of said resonating laser light which will have minimum loss defining a lasing wavelength;
- .DELTA.n=the birefringence of said first tuning plate defined as the difference in the indices of refraction along said two principal displacement directions in the anisotropic material of said first tuning plate at the lasing wavelength .lambda.;
- T=the thickness of said birefringent first tuning plate;
- m=an order number indicating the number of full wavelengths of phase retardation the light will experience in passing through the birefringent first tuning plate;
- .theta.=the angle of incidence of said laser light beam in the cavity on said surface of the plate;
- n=the average index of refraction of the birefringent material of said first tuning plate at said lasing wavelength .lambda.; and,
- .phi.=a tuning angle equal to .alpha.+.pi./4 where .alpha. is the angle between the projection of said optic axis of the birefringent first tuning plate on said surface of said birefringent first tuning plate upon which the incoming resonating laser light beam is incident to a plane containing both the direction of propagation vector of said resonating laser light beam and a normal to said surface upon which said resonating laser light beam is incident;
- said thickness T defining a family of tuning curves each of which is of a single order m and defining a relationship between tuning angle and lasing wavelength and said thickness T being chosen such that a single order tuning curve covers a desired range of lasing wavelengths;
- a substrate of nonbirefringent material located on each surface of said first tuning plate upon which said resonating laser light beam is incident and through which light resonating in said cavity passes and having an index of refraction which substantially matches the average index of refraction of said birefringent first tuning plate and having a thickness sufficient to suppress interference effects such as satellite lobes in the autocorrelation function for pulse shape for pulses of greater than 2 picoseconds duration.
- 35. A solid state laser comprising:
- a solid lasing medium;
- a resonator cavity including at least two mirrors and defining an axis for resonating light between said two mirrors which passes through said jet dye;
- a first tuning plate of birefringent material having a predetermined thickness T which defines a family of tuning curves, said thickness T chosen so that a single mode curve in the family of tuning curves covers a predetermined range of desired lasing wavelengths, and said first tuning plate being located such that light resonating in said cavity along said axis passes through said first tuning plate and makes Brewster's angle with the normal to the surface of said first plate and having a layer of material having an index of refraction which substantially matches the index of refraction of said first tuning plate on each surface of said first tuning plate through which light resonating in said cavity passes and having a thickness sufficient to suppress interference effects;
- at least a second tuning plate of birefringent material having a thickness which is an integer multiple of the thickness of said first tuning plate and located such that light resonating in said cavity along said axis passes through said second tuning plate and oriented such that light incident on said second tuning plate makes Brewster's angle with said first tuning plate, and having an optic axis which is parallel with the optic axis of said first tuning plate; and
- a third non-birefringent plate having a thickness which is an integer multiple of the thickness of said second plate and oriented such that light resonating in said cavity passes through said third plate and makes Brewster's angle with the normal to the surface of said third non-birefringent plate; and
- a layer of nonbirefringent material on each surface of each of said first, second and third tuning plates through which said resonating light beam passes having an index of refraction which matches the average index of refraction of the birefringent material of said tuning plate to which each layer is optically coupled.
- 36. A tuning apparatus for a dye laser having a resonator cavity in which a beam of laser light is resonating therein defining an axis comprising:
- a first tuning plate of birefringent material having two different indices of refraction along two different principal displacement directions and having an optic axis and having at least two surfaces upon which said resonating light beam is incident having a thickness T defined according to the following equation: ##EQU25## where, .lambda.=the wavelength of said resonating laser light which will have minimum loss defining a lasing wavelength;
- .DELTA.n=the birefringence of said first tuning plate defined as the difference in the indices of refraction along said two principal displacement directions in the anisotropic material of said first tuning plate at the lasing wavelength .lambda.;
- T=the thickness of said birefringent first tuning plate;
- m=an order number indicating the number of full wavelengths of phase retardation the light will experience in passing through the birefringent first tuning plate where each value of m defines a tuning curve for a specific value of T;
- .theta.=the angle of incidence of said laser light beam in the cavity on said surface of the plate;
- n=the average index of refraction of the birefringent material of said first tuning plate at said lasing wavelength .lambda.; and,
- .phi.=a tuning angle equal to .alpha.+.pi./4 where .alpha. is the angle between the projection of said optic axis of the birefringent first tuning plate on said surface of said birefringent first tuning plate upon which the incoming resonating laser light beam is incident to a plane containing both the direction of propagation vector of said resonating laser light beam and a normal to said surface upon which said resonating laser light beam is incident;
- said thickness defining a family of tuning curves that relate tuning angle .phi. to lasing wavelength, T being chosen such that a tuning curve having a single value m covers a range of lasing wavelengths of a selected dye within a predetermined range of tuning angles, .phi.; and
- a non-birefringent glass plate of a thickness between 1.0 and 1.5 millimeters having an index of refraction substantially matched to at least one index of refraction of said tuning plate and located in said resonator cavity so as to be in path of said resonating light beam and optically contacting said first tuning plate so as to minimize or avoid interference effects such as satellite lobes.
- 37. A tuning apparatus for a dye laser having a resonator cavity having a resonating light beam of laser light therein defining an axis comprising:
- a first tuning plate of birefringent material having two different indices of refraction along two different principal displacement directions and having an optic axis and having at least two surfaces upon which said resonating light beam is incident having a thickness T defined according to the following equation: ##EQU26## where, .lambda.=the wavelength of said resonating laser light which will have minimum loss defining a lasing wavelength;
- .DELTA.n=the birefringence of said first tuning plate defined as the difference in the indices of refraction along said two principal displacement directions in the anisotropic material of said first tuning plate at the lasing wavelength .lambda.;
- T=the thickness of said birefringent first tuning plate;
- m=an order number indicating the number of full wavelengths of phase retardation the light will experience in passing through the birefringent first tuning plate where for a specific value of T the family of integers m defines a family of tuning curves;
- .theta.=the angle of incidence of said laser light beam in the cavity on said surface of the plate;
- n=the average index of refraction of the birefringent material of said first tuning plate at said lasing wavelength .lambda.; and,
- .phi.=a tuning angle equal to .alpha.+.pi./4 where .alpha. is the angle between the projection of said optic axis of the birefringent first tuning plate on said surface of said birefringent first tuning plate upon which the incoming resonating laser light beam is incident to a plane containing both the direction of propagation vector of said resonating laser light beam and a normal to said surface upon which said resonating laser light beam is incident;
- said thickness T being chosen such that a single order tuning curve relating tuning angle .phi. to lasing wavelength covers a desired range of lasing wavelengths over a predetermined range of tuning angles, .phi., where each tuning curve relates the wavelength suffering minimum loss to tuning angle .phi.;
- a second tuning plate of birefringent material having a thickness which is an integer multiple of the thickness of said first tuning plate and oriented at Brewster's angle in said resonator cavity such said light beam resonating therein passes through said second tuning plate; and
- a non-birefringent glass plate having an index of refraction substantially matched to at least one said index of refraction of said first tuning plate and said second tuning plate and located in said resonating cavity so as to be in the path of light beam resonating therein and optically contacting said first and second tuning plates so as to minimize or avoid satellite lobes in the autocorrelation function of pulse shape for pulse durations of greater than 2 picoseconds; and
- a nonbirefringent plate located in said cavity at Brewster's angle and made of a polarization selective material such that light resonating in said cavity and passing therethrough which does not have p-polarization will suffer sufficient loss to extinguish lasing.
- 38. A tuning apparatus for a dye laser having a resonator cavity having a resonating light beam of laser light therein defining an axis comprising:
- a first tuning plate of birefringent material having two different indices of refraction along two different principal displacement directions and having an optic axis and having at least two surfaces upon which said resonating light beam is incident having a thickness T defined according to the following equation: ##EQU27## where, .lambda.=the wavelength of said resonating light which will have minimum loss and defining the lasing wavelength;
- .DELTA.n=the birefringence of said first tuning plate defined as the difference in the indices of refraction along said two principal displacement directions in the anisotropic material of said first tuning plate at the lasing wavelength .lambda.;
- T=the thickness of said birefringent first tuning plate;
- m=an order number indicating the number of full wavelengths of phase retardation the light will experience in passing through the birefringent first tuning plate;
- .theta.=the angle of incidence of said laser light beam in the cavity on said surface of the plate;
- n=the average index of refraction of the birefringent material of said first tuning plate at said lasing wavelength .lambda.; and,
- .phi.=a tuning angle equal to .alpha.+.pi./4 where .alpha. is the angle between the projection of said optic axis of the birefringent first tuning plate on said surface of said birefringent first tuning plate upon which the incoming resonating laser light beam is incident to a plane containing both the direction of propagation vector of said resonating laser light beam and a normal to said surface upon which said resonating laser light beam is incident;
- said thickness T defining a family of tuning curves each of which relates tuning angle .phi. to lasing wavelengths, T being chosen such that a single order tuning curve having a selected value m covers a desired range of lasing wavelengths for the dye in use;
- a non-birefringent glass plate having an index of refraction substantially matched to an index of refraction of said first birefringent tuning plate and located in said resonator cavity so as to be in path of light resonating in said resonator cavity and optically contacting said first birefringent tuning plate so as to minimize or avoid satellite lobes for pulse widths greater than 2 picoseconds; and
- a plate of non-birefringent material oriented at Brewster's angle to said light beam resonating in said cavity and made of a polarization selective which passes p-polarized light but imposes losses on non-p-polarized light material so as to create sufficient losses on wavelengths resonating in said cavity having other than p-polarization so as to extinguish lasing for non-p-polarized light.
- 39. In a laser having a birefringent filter plate for tuning the wavelength of light resonating in the cavity of said laser the improvement comprising a layer of nonbirefringent material coated on each surface of said birefringent filter plate through which light resonating in said cavity passes having a thickness selected to minimize satellite lobes.
- 40. The apparatus of claim 39 wherein said nonbirefringent material has a thickness between 1 to 1.5 mm or sufficient to suppress interference effects such as tuning discontinuities on the light resonating in said cavity at the lasing wavelength.
- 41. The apparatus of claim 39 wherein said nonbirefringent material is KZF1 glass.
- 42. The apparatus of claim 41 wherein said KZF1 glass has a thickness from 0.5 to 1.5 millimeters, preferably 1 millimeter.
- 43. A solid state laser comprising:
- a lasing medium;
- means for applying pump energy to said solid state lasing medium;
- a resonator cavity to guide light emitted from said lasing medium resonating in said cavity;
- a rotatable birefringent plate at Brewster's angle positioned in said cavity such that light resonating therein passes therethrough; and
- a layer of nonbirefringent material on each surface of said birefringent plate through which said resonating light passes having an index of refraction which substantially matches the average index of refraction of said birefringent plate and having a thickness between 1 and 1.5 mm so as to minimize satellite lobes.
- 44. The apparatus of claim 42 wherein said nonbirefringent material is KZF1 glass.
- 45. The apparatus of claim 43 wherein said lasing medium is a dye jet and further comprising a fixed plate of nonbirefringent material in said cavity such that said resonating light makes Brewster's angle with the normal to said fixed plate, said fixed plate being of a material and orientation to impose substantial losses on resonating wavelengths having other than p-polarization.
BACKGROUND OF THE INVENTION
This invention is a continuation in part of a U.S. patent application of the same title filed Oct. 21, 1988, Ser. No. 07/260,930, now abandoned.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
4914664 |
Woodward |
Apr 1990 |
|
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
260930 |
Oct 1988 |
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